Subjective Cognitive Decline (SCD), an increasingly popular entity, refers to the presence of an isolated subjective/self-reported cognitive decline in older individuals without any abnormal clinical or neuropsychological examination. Although these individuals perform in the normal range on a bunch of standardized neuropsychological tests, they are still at risk of developing Alzheimer’s disease, and are currently being scrutinized by Azheimer’s researchers. The conceptual paper published by the SCD initiative in 2014 emphasized the interest of studying these individuals in the context of preclinical AD, but also emphasized that SCD was an umbrella term and that the aspects of SCD associated with early features of AD need refinement.

In this paper, we assessed cognitive, affective and neuroimaging (structural MRI and amyloid-PET) indices in 2 groups of cognitively normal older individuals classified as SCD according to different approaches: i) individuals who consulted at a memory clinic because of their subjective feeling of cognitive decline (SCD-clinic) and ii) individuals recruited from the community for our academic study of aging who scored high on a self-rated questionnaire of cognitive difficulties (SCD-community).

Both SCD groups were associated with a burden of neuroimaging biomarker abnormalities and subclinical affective symptomatology, but that these pattern varied according to the definition of SCD: anxiety and amyloid-plaques were statistically increased in both groups with SCD compared to a control group, while subclinical depression and brain atrophy were marked in the medical-help seeking group only.

These results further validate the concept of SCD in both community and clinic-based groups but also highlight the heterogeneous nature of SCD depending on study characteristics. These results has major impact on future studies in preclinical AD, notably in terms of enrichment for clinical trials.

This is an happy end for a long paper story. A preliminary version of the study was initially presented at the Alzheimer’s Association International Conference in Boston in 2013 (see abstract). We then included (many!) more participants in our study, and after a few unsuccessful submissions/modifications as well as additional analyses, the manuscript got accepted in a perfectly fitted journal.

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About Renaud La Joie

PhD in neuroscience/neuropsychology.
I am interested in age-related neurodegenerative diseases including Alzheimer’s disease & related disorders.
My research involves multimodal neuroimaging and neuropsychological tools, as complementary approaches are required to better characterize - and hopefully understand - these disorders. From a more fundamental perspective, studying the diseased brain will also contribute to further our knowledge on the neural basis of cognitive functions in the normal brain.